Buggy code:
public void removeMouseListener ( MouseListener listener ) { } public void removeMouseMoveListener ( MouseMoveListener listener ) { } public void removePaintListener ( PaintListener listener ) { } public void removeTraverseListener ( TraverseListener listener ) { } void showWidget ( boolean visible ) { } boolean sendFocusEvent ( int type ) { } public void setBackground ( Color color ) { } void setBackgroundPixel ( int pixel ) { } public void setBounds ( int x , int y , int width , int height ) { } void setBounds ( int x , int y , int width , int height , int flags ) { } void setBounds ( int x , int y , int width , int height , int flags , boolean defer ) { } public void setBounds ( Rectangle rect ) { } public void setCapture ( boolean capture ) { } void setCursor ( ) { } public void setCursor ( Cursor cursor ) { } void setDefaultFont ( ) { } public void setEnabled ( boolean enabled ) { } boolean setFixedFocus ( ) { } public boolean setFocus ( ) { } public void setFont ( Font font ) { } public void setForeground ( Color color ) { } void setForegroundPixel ( int pixel ) { } public void setLayoutData ( Object layoutData ) { } public void setLocation ( int x , int y ) { } public void setLocation ( Point location ) { } public void setMenu ( Menu menu ) { } boolean setRadioFocus ( ) { } boolean setRadioSelection ( boolean value ) { } public void setRedraw ( boolean redraw ) { } boolean setSavedFocus ( ) { } public void setSize ( int width , int height ) { } public void setSize ( Point size ) { } boolean setTabGroupFocus ( ) { } boolean setTabItemFocus ( ) { } public void setToolTipText ( String string ) { } public void setVisible ( boolean visible ) { } void sort ( int [ ] items ) { } void subclass ( ) { } public Point toControl ( int x , int y ) { } public Point toControl ( Point point ) { } public Point toDisplay ( int x , int y ) { } public Point toDisplay ( Point point ) { } int topHandle ( ) { } boolean translateAccelerator ( MSG msg ) { } boolean translateMnemonic ( Event event , Control control ) { } boolean translateMnemonic ( MSG msg ) { } boolean translateTraversal ( MSG msg ) { } boolean traverse ( Event event ) { } public boolean traverse ( int traversal ) { } boolean traverseEscape ( ) { } boolean traverseGroup ( boolean next ) { } boolean traverseItem ( boolean next ) { } boolean traverseMnemonic ( char key ) { } boolean traversePage ( boolean next ) { } boolean traverseReturn ( ) { } void unsubclass ( ) { } public void update ( ) { } void update ( boolean all ) { } boolean updateFont ( Font oldFont , Font newFont ) { } void updateLayout ( boolean resize , boolean all ) { } CREATESTRUCT widgetCreateStruct ( ) { } int widgetExtStyle ( ) { } int widgetParent ( ) { } int widgetStyle ( ) { } public boolean setParent ( Composite parent ) { } abstract TCHAR windowClass ( ) { } abstract int windowProc ( ) { } int windowProc ( int hwnd , int msg , int wParam , int lParam ) { } LRESULT WM_ACTIVATE ( int wParam , int lParam ) { } LRESULT WM_CAPTURECHANGED ( int wParam , int lParam ) { <START_BUG> return null ; <END_BUG> } LRESULT WM_CHAR ( int wParam , int lParam ) { } LRESULT WM_CLEAR ( int wParam , int lParam ) { } LRESULT WM_CLOSE ( int wParam , int lParam ) { } LRESULT WM_COMMAND ( int wParam , int lParam ) { } LRESULT WM_CONTEXTMENU ( int wParam , int lParam ) { } LRESULT WM_CTLCOLOR ( int wParam , int lParam ) { } LRESULT WM_CUT ( int wParam , int lParam ) { } LRESULT WM_DESTROY ( int wParam , int lParam ) { } LRESULT WM_DRAWITEM ( int wParam , int lParam ) { } LRESULT WM_ENDSESSION ( int wParam , int lParam ) { } LRESULT WM_ENTERIDLE ( int wParam , int lParam ) { } LRESULT WM_ERASEBKGND ( int wParam , int lParam ) { } LRESULT WM_GETDLGCODE ( int wParam , int lParam ) { } LRESULT WM_GETFONT ( int wParam , int lParam ) { } LRESULT WM_GETOBJECT ( int wParam , int lParam ) { } LRESULT WM_GETMINMAXINFO ( int wParam , int lParam ) { } LRESULT WM_HOTKEY ( int wParam , int lParam ) { } LRESULT WM_HELP ( int wParam , int lParam ) { } LRESULT WM_HSCROLL ( int wParam , int lParam ) { } LRESULT WM_IME_CHAR ( int wParam , int lParam ) { } LRESULT WM_IME_COMPOSITION ( int wParam , int lParam ) { } LRESULT WM_INITMENUPOPUP ( int wParam , int lParam ) { } LRESULT WM_INPUTLANGCHANGE ( int wParam , int lParam ) { } LRESULT WM_KEYDOWN ( int wParam , int lParam ) { } LRESULT WM_KEYUP ( int wParam , int lParam ) { } LRESULT WM_KILLFOCUS ( int wParam , int lParam ) { } LRESULT WM_LBUTTONDBLCLK ( int wParam , int lParam ) { } LRESULT WM_LBUTTONDOWN ( int wParam , int lParam ) { } LRESULT WM_LBUTTONUP ( int wParam , int lParam ) { } LRESULT WM_MBUTTONDBLCLK ( int wParam , int lParam ) { } LRESULT WM_MBUTTONDOWN ( int wParam , int lParam ) { } LRESULT WM_MBUTTONUP ( int wParam , int lParam ) { } LRESULT WM_MEASUREITEM ( int wParam , int lParam ) { }

Fix:
return wmCaptureChanged ( handle , wParam , lParam ) ;